Many tree climbers or steps have been provided according to the prior art. However, these have all been characterized by numerous disadvantages. For example, they are not readily attached to or screwable into a tree or post upon which desired to be mounted. Further, they suffer from the fact that torque to be applied thereto in the mounting by screwing into a tree or post cannot be maximized, so that maximum hand pressure is frequently inadequate for the purpose of mounting the same on a selected tree or post. Also, numerous of such means have been provided in the past which failed to provide adequate contact between a portion of the step and a vertical surface of the tree or post upon which desired to be mounted, thus rendering the device less structurally stable and secure than desired after mounting of the same. Despite all these shortcomings, innumerable types and forms of tree climbers or steps, which are allegedly mountable as by screwing into a vertical surface of a tree or post, are still being promoted to the general public with their ensuing disappointing use effectiveness, stability, strength, and security. All of the foregoing shortcomings are eliminated by provision of the tree climber or step according to the present invention.